Kidney Function and Care

The kidneys are a pair of bean shaped organs with one on either side of the spine in the region of the mid-back to lower mid-back. Each kidney is supplied with a renal artery and renal vein for the supply and removal of blood to the kidney.

Functions of the kidney:

• To remove toxic waste products from the body
• To remove excess water and salts
• To control the blood pressure
• To stimulate the production of red blood cells by producing a protein known as erythropoietin
• To help keep calcium and phosphate in balance for healthy bones

Signs that the kidneys are not functioning properly

In the early stages of many kidney diseases, there are no symptoms at all. Kidney function needs to be quite badly damaged before any symptoms become noticeable. At first these are usually very vague and non-specific and easily confused with many other conditions. A general slowing down and tiredness are common. Later symptoms may include loss of appetite, itch, poor sleep etc.  Following symptoms may be indicative of kidney damage:

• Decrease in the amount of urine or frequency
• Pain or urgency with urination
• Dark urine, blood in urine
• Fatigue, muscle weakness
• Swelling in feet or ankles
• Nausea or vomiting
• Confusion, seizure

How is kidney damage diagnosed?

Two commonly used blood tests for assessment of the kidney function are described below:

Blood Urea Nitrogen (BUN): The waste product from the breakdown of protein is called urea. Urea circulates in the blood until it is filtered out by the kidneys and excreted in the urine. If the kidneys are not functioning properly, there will be excess urea in the bloodstream. Under normal conditions, BUN levels range from 10-25 mg/dl of blood.

Creatinine: Some of the energy for your muscles is derived from burning a substance called creatine. Creatinine is the waste product left after the breakdown of creatine. The kidneys are normally able to filter out large amounts of creatinine on a daily basis. However, when your kidneys are not functioning properly, your creatinine levels will increase. Under normal conditions, creatinine levels range from 0.7-1.4 mg/dl of blood.

Recommended foods for patients with kidney disease

You may need to change what you eat to manage your chronic kidney disease (CKD). Work with a registered dietitian to develop a meal plan that includes foods that you enjoy eating while maintaining your kidney health.

The steps below will help you eat right as you manage your kidney disease. The first three steps (1-3) are important for all people with kidney disease. The last two steps (4-5) may become important as your kidney function goes down.

The first steps to eating right

Step 1: Choose and prepare foods with less salt and sodium

Why? To help control your blood pressure. Your diet should contain less than 2,300 milligrams of sodium each day.

• Buy fresh food often. Sodium (a part of salt) is added to many prepared or packaged foods you buy at the supermarket or at restaurants.
• Cook foods from scratch instead of eating prepared foods, “fast” foods, frozen dinners, and canned foods that are higher in sodium. When you prepare your own food, you control what goes into it.
• Use spices, herbs, and sodium-free seasonings in place of salt.
• Check for sodium on the Nutrition Facts label of food packages. A Daily Value of 20 percent or more means the food is high in sodium.
• Try lower-sodium versions of frozen dinners and other convenience foods.
• Rinse canned vegetables, beans, meats, and fish with water before eating.

Look for food labels with words like sodium free or salt free; or low, reduced, or no salt or sodium; or unsalted or lightly salted.

Step 2: Eat the right amount and the right types of protein

Why? To help protect your kidneys. When your body uses protein, it produces waste. Your kidneys remove this waste. Eating more protein than you need may make your kidneys work harder.

• Eat small portionsof protein foods.
• Protein is found in foods from plants and animals. Most people eat both types of protein. Talk to your dietitian about how to choose the right combination of protein foods for you.

Animal-protein foods:

• Chicken
• Fish
• Meat
• Eggs
• Dairy

A cooked portion of chicken, fish, or meat is about 2 to 3 ounces or about the size of a deck of cards. A portion of dairy foods is ½ cup of milk or yogurt, or one slice of cheese.

Plant-protein foods:

• Beans
• Nuts
• Grains

A portion of cooked beans is about ½ cup, and a portion of nuts is ¼ cup. A portion of bread is a single slice, and a portion of cooked rice or cooked noodles is ½ cup.

Step 3: Choose foods that are healthy for your heart

Why? To help keep fat from building up in your blood vessels, heart, and kidneys. To help keep fat from building up in your blood vessels, heart, and kidneys.

• Grill, boil, bake, roast, or stir-fry foods, instead of deep frying.
• Cook with nonstick cooking spray or a small amount of olive oil instead of butter.
• Trim fat from meat and remove skin from poultry before eating.
• Try to limit saturatedand trans fats. Read the food label.

Heart-healthy foods:

• Lean cuts of meat
• Poultry without the skin
• Fish
• Beans
• Vegetables
• Fruits
• Low-fat or fat-free milk, yogurt, and cheese

Choose heart-healthy foods to help protect your blood vessels, heart, and kidneys.

Limit alcohol
Drink alcohol only in moderation: no more than one drink per day if you are a woman, and no more than two if you are a man. Drinking too much alcohol can damage the liver, heart, and brain and cause serious health problems. Ask your health care provider how much alcohol you can drink safely.

The next steps to eating right

As your kidney function goes down, you may need to eat foods with less phosphorus and potassium. Your health care provider will use lab tests to check phosphorus and potassium levels in your blood, and you can work with your dietitian to adjust your meal plan.

Step 4: Choose foods and drinks with less phosphorus

Why? To help protect your bones and blood vessels. When you have CKD, phosphorus can build up in your blood. Too much phosphorus in your blood pulls calcium from your bones, making your bones thin, weak, and more likely to break. High levels of phosphorus in your blood can also cause itchy skin, and bone and joint pain.

• Some fresh meat and poultry can have added phosphorus.

Foods Lower in Phosphorus ·        Fresh fruits and vegetables ·        Breads, pasta, rice ·        Rice milk (not enriched) ·        Corn and rice cereals ·        Light-colored sodas/pop, such as lemon-lime or homemade iced tea

Foods Higher in Phosphorus ·        Meat, poultry, fish ·        Bran cereals and oatmeal ·        Dairy foods ·        Beans, lentils, nuts ·        Dark-colored sodas/pop, fruit punch, some bottled or canned iced teas that have added phosphorus

Your health care provider may talk to you about taking a phosphate binder with meals to lower the amount of phosphorus in your blood. A phosphate binder is a medicine that acts like a sponge to soak up, or bind, phosphorus while it is in the stomach. Because it is bound, the phosphorus does not get into your blood. Instead, your body removes the phosphorus through your stool.

Step 5: Choose foods with the right amount of potassium

Why? To help your nerves and muscles work the right way. Problems can occur when blood potassium levels are too high or too low. Damaged kidneys allow potassium to build up in your blood, which can cause serious heart problems. Your food and drink choices can help you lower your potassium level, if needed.

• Salt substitutes can be very high in potassium. Read the ingredient label. Check with your provider about using salt substitutes.
• Drain canned fruits and vegetables before eating.

Foods Lower in Potassium ·        Apples, peaches ·        Carrots, green beans ·        White bread and pasta ·        White rice ·        Rice milk (not enriched) ·        Cooked rice and wheat cereals, grits ·        Apple, grape, or cranberry juice

Foods Higher in Potassium ·        Oranges, bananas, and orange juice ·        Potatoes, tomatoes ·        Brown and wild rice ·        Bran cereals ·        Dairy foods ·        Whole-wheat bread and pasta ·        Beans and nuts

Some medicines also can raise your potassium level. Your health care provider may adjust the medicines you take.

Why is it important to keep track of how much liquid I eat or drink?

You may feel better if you keep track of and limit how much liquid you eat and drink. Excess fluid can build up in your body and may cause

• swelling and weight gain between dialysis sessions
• changes in your blood pressure
• your heart to work harder, which can lead to serious heart trouble
• a buildup of fluid in your lungs, making it hard for you to breathe

Hemodialysis removes extra fluid from your body. However, hemodialysis can remove only so much fluid at a time safely. If you come to your hemodialysis with too much fluid in your body, your treatment may make you feel ill. You may get muscle cramps or have a sudden drop in blood pressure that causes you to feel dizzy or sick to your stomach.

Your health care provider can help you figure out how much liquid is right for you.

One way to limit how much liquid you have is to limit the salt in the foods you eat. Salt makes you thirsty, so you drink more. Avoid salty foods such as chips.

What foods count as liquid and why?

Foods that are liquid at room temperature, such as soup, contain water. Most fruits and vegetables contain water, such as melons, grapes, apples, oranges, tomatoes, lettuce, and celery. When you count up how much liquid you have in a day, be sure to count these foods. Any food that is liquid at room temperature contains water. Some foods, like most fruits and vegetables, are not liquid at room temperature but also add to the total liquid amount you eat.Work with your dietitian to set a goal for how much liquid you can have each day. Keep track of the liquids you drink and other foods you eat.

What do I need to know about calories?

Vegetable oils—such as olive oil, canola oil, and safflower oil—are good sources of calories and are the healthiest way to add fat to your diet if you need to gain weight. Use them generously on breads, rice, and noodles only if your dietitian tells you to add calories to your diet.Butter and margarines are rich in calories; however, they are mainly saturated fat. Saturated fats and trans fats can clog your arteries. Use them less often. Soft margarine that comes in a tub is better than stick margarine. Choose a soft margarine with less saturated and trans fats.

Talk with your dietitian about the types and amounts of fat you need in your diet. Everyone will have different needs that a renal dietitian can help address.

Hard candy, sugar, honey, jam, and jelly provide calories and energy without fat or adding other things that your body does not need. If you have diabetes, be careful about eating sweetsand talk with your renal dietitian before adding sweets to your food plan.

If you are overweight, your renal dietitian can work with you to reduce the total calories you eat each day.

Should I take vitamin and mineral supplements?

You may not get enough vitamins and minerals in your diet because you have to avoid so many foods. Hemodialysis also removes some vitamins from your body. Your health care provider may prescribe a vitamin and mineral supplement designed specifically for people with kidney failure.

Warning: Do not take nutritional supplements you can buy over the counter. These supplements may contain vitamins or minerals that are harmful to you. For safety reasons, talk with your health care provider before using probiotics, dietary supplements, or any other medicine together with or in place of the treatment your health care provider prescribes.

Talk with your health care provider before using probiotics, dietary supplements, or any other medicine together with or in place of the treatment your health care provider prescribes.